170  Constituents  of  Taraxacum  Root.  {.^S^iSSl™ 
aqueous  alkalis,  as  already  described.  The  ammonium  carbonate 
extract  thus  obtained,  when  acidified,  yielded  a  gum-like  product, 
which  was  esterified.  The  acid  was  then  regenerated  from  the 
ester  and  crystallised  several  times  from  ethyl  acetate,  when  it 
separated  in  flat  needles  melting  at  144 — 1460,  and  amounted  to 
about  0.4  gram.  It  was  identical  with  the  small  portion  (0.05  gram) 
of  acid  first  obtained.  By  the  subsequent  extraction  of  both 
portions  of  the  original  ethereal  extract  with  sodium  carbonate 
and  sodium  hydroxide  respectively,  only  small  amounts  of  dark- 
colored,  amorphous  products  were  obtained,  from  which  nothing 
definite  could  be  isolated. 
The  above-described  acid  was  dried  at  105 0  and  analysed: 
0.0632  gave  0.1451  C02  and  0.0294  H20.    C— 62.6;  H=5-2. 
0.0818     "     0.1894  C02    "    0.0379  H20.    0=63.1;  H— 5.1. 
0.1009  neutralised  32.5  c.c.  AV50-KOH.    M.W.   ( monocarboxylic 
acid)  =  155. 
C8H803  requires  0=63.1 ;  £[=.5.3  per  cent.  M.W.=I52. 
A  determination  of  the  molecular  weight  of  the  acid  by  Barger's 
microscopic  method  was  kindly  made  for  us  by  Mr.  A.  J.  Ewins, 
B.Sc,  with  the  following  result : 
0.048  in  1. 196  of  absolute  alcohol,  using  a-naphthol  as  the 
standard,  was  between  0.26  and  0.275  mol.  Mean  M.W.= 
150. 
The  acid  was  soluble  in  cold,  and  more  readily  in  warm,  water, 
as  also  in  alcohol,  ether,  ethyl  acetate,  and  acetone,  but  only  slightly 
so  in  benzene  or  the  higher  boiling  fractions  of  petroleum.  Its 
dilute  aqueous  solution  gave  no  perceptible  coloration  with  ferric 
chloride.  With  Million's  reagent  it  yielded  the  deep  red  color 
characteristic  of  the  aromatic  monohydroxy- acids  (Ber.,  1879,  12, 
1452)  ;  and  a  trace  of  the  substance,  when  heated  with  soda-lime, 
gave  a  distinct  phenolic  odor. 
A  consideration  of  the  composition  and  characters  of  the  above- 
described  substance  indicated  it  to  be  />-hydroxyphenylacetic  acid, 
which  has  not  previously  been  observed  to  occur  as  such  in  the 
vegetable  kingdom.  It  was  obtained  by  A.  G.  Perkin  and  Newbury 
(Trans.,  1899,  75,  834)  by  the  action  of  potassium'  hydroxide  on 
genistein,  and  Ewins  and  Laidlaw  (/.  Physiol,  1910,  41,  78)  have 
